Safety-stop for switches.



C. H. HILL.

SAFETY STOP FOR SWITCHES.

APPLICATION FILED NOV. I3, 1915.

Inventor: Charles H. Hill,

His flttorneg.

I m ES H. HILL, OF SCHENEC'IADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

SAFETY-STOP FOR SWITCHES.

Specification of Letters Patent.

Patented May at, acre.

To all whom it may concern:

Be it known that I, CHARLES H. HILL, acitizen of the United States,residing at Schenectad in the county of Schenectady, State of, ew York,have invented certain new and useful Improvements in Safety- Stops forSwitches, of which the following is a specification.

The object of my invention is to provide a safety device for knife bladeswitches to prevent them from being closed accidentally. If a doublethrow knife blade switch is mounted so that the blades swing in avertical direction there is a tendency for the blades to fall and makecontact when the switch is open. There is also danger that such switcheswill he accidentally closed by reason of. carelessness onthe part oftheattendant. The more particular object of my invention is to preventaccidents by reason of the closing of knife blade switches of theabove-mentioned type at times when it is desired that they should remainopen. It is not limited in its utility to this particu lar type ofswitch but may be employed with any form of knife blade switchirrespective of the way in which it is mounted.

My invention will best be understood by reference to the followingdescription taken in connection with the accompanying drawing in which Ihave shown a side view of a switch provided with one of my devices. As

here shown the single pole double throw:

knife blade switch 1 has upper contact cli s 2 and lower contact cli s 3mounted on t e base 4 in such a way t at the blade which is pivoted at 5swings in a vertical direction. When the switch is open there is atendency for the blade to fall and make contact with the lower clips.This tendency increases after the switch has been in service for sometime and the usual friction in the pivotal mounting has decreased. Thereis also danger that a careless attendant will accidenta ly touch thehandle 6 and close the switch on the lower contact. It has beencustomary heretofore to avoid this danger by providing separate blocksof in-. sulating material which fit into the clips 3 and prevent theblade fi'om making contact therewith. Such blocks however are easilymisplaced and lost and are therefore inefiicient for roviding thedesired safeguard. This dlsadvantage is overcome by my device whichcomprises a blade 7 having an insulating knob 8 on the end thereof andwhich is pivotally mounted at the point 9 adjacent the clips 3. When theswitch is opened the device, which for convenience of description I terma safety stop, is placed in the osition shown in the drawing. The bladei is made to fit the contact clips 3 and its upward movement is limitedby the usual shoulder 10, indicated by dotted lines, which is providedto limit the movement of the switch blade toward the base. The

safety stop is frictionally held in this '90 7 sition by the clips 3 andit will be apparent that it will be impossible to close the switch onthe lower contacts until the safety stop is manually thrown down to theposition indicatedby dotted lines where it does not interfere in any waywith the operation of the switch.

While I have described and illustrated the application of my inventionto a single pole double throw switch, it will be apparent that a stopsuch as the one I have shown will be equally effective with switcheshaving more than one pole and that it may be applied to any knife bladeswitch, if desired, irrespective of the way in which it is mounted.

What I claim as new and desire tosecure by Letters Patent of the UnitedStates, is 2- 1. The combination with a switch having a knife blade andcooperating contact clips,

of a safety stop comprising a blade pivotally mounted adjacent one ofthe contact clips and adapted to be held in position by'said contactclips when the switch is open and an insulating member on said bladeadapted to limit the movementof the knife blade.

2. The combination with a switch having a knife blade and cooperatingcontact clips, of means for limiting the motion of the knife bladetoward the contacts comprising a member pivotally mounted adjacent oneof the contact clips so as to swing in the same T direction as the knifeblade and adapted to roof be held in position by the contact clips so asto limit the motion of the knife blade.

3. The combination with a switch having a knife blade and cooperatincontact clips,

5 of a safety stop comprising a lade pivotally mounted adjacent one ofthe contact clips so that its path of travel is partly coincident withthat of the knife blade and adapted to be held in position by saidcontact clips so as to limit the movement of said knife 10 blade.

In witness whereof, I have hereunto set my hand this 12th day ofNovember 1915.

CHARLES H. HILL.

